The present invention relates to pressure vessels, and more particularly, to pressure vessels for the safe transportation of low pressure liquefiable gases up to 1000 Kgs. capacity.
Cylindrical vessels having circumferential welded joints have been known for the transport of liquefiable gases. These joints were prepared by a forged welding process. Further, no radiography on those joints was carried out. Without radiography of each joint, the extent of bonding in the circumferential weld joints was not known. Consequently, the safety of the cylinders was suspect.
Conventionally in the drum art, a chime is an integral part of the drum which can extend radially outwardly from its lateral surface. Often used for rolling the drum, chimes can also be provided at the ends of the drum for xe2x80x9chandlingxe2x80x9d by cranes. Additionally, a chime can be considered to extend axially of a drum or pressure vessel. When used in conjunction with a lifting bar, such a pressure vessel or drum can be moved by a crane.
The present invention is particularly suitable for the transport of low pressure liquefiable gases, such as chlorine, sulphur dioxide, ammonia etc.
In view of the foregoing disadvantages inherent in the known types of liquefiable gas pressure cylinder now present in the prior art, the present invention provides a Liquefiable gas pressure cylinder wherein the same is arranged to have overpressure protection built-in for assured safety. This is enabled by the design of the heads and by the particular method and manner of construction of the cylinder.
As such, the general purpose of the present invention, which will be described subsequently in greater detail, is to provide a new and improved liquefiable gas pressure cylinder which has all the advantages of the prior art liquefiable gas pressure cylinder and none of the disadvantages.
To attain this, the present invention provides a liquefiable gas pressure cylinder comprising: a shell; and heads fusion welded at opposites ends of the shell; wherein side ends where the heads are joined to the shell are crimped radially inward to each end to form chimes.
The liquefiable gas pressure cylinder as above can have the shell be a straight cylinder having a single longitudinal welded seam defining the cylinder body and opposite axial end portions; the heads be circular each having a domed center portion and a flanged periphery, the flanged periphery having a cylinder portion surrounding the domed center portion and a radially extending edge portion, an outer diameter of the cylinder portion being equal to an internal diameter of the shell so that when the heads are mounted into the shell with the domed center portion extending axially inwardly, the cylinder portion being press-fitted into the end portions of the shell.
The liquefiable gas pressure cylinder as above can have a gap defined between each the end axial edge of the end portions of the shell and a side face of the radially extending edge portion of the head; the end axial edge of the shell be beveled at a first angle to a radius of the shell; the side face of the radially extending edge portion of the head be machined to have a sharper radius and a corresponding face bevel of at a second angle; and an overlap of the shell with the cylinder portion of the head form a lap joint configuration with the gap, the shell and the heads being joined by fusion welding in the gap.
The liquefiable gas pressure cylinder as above can have the heads be provided with at least one tapped hole at a radius distance from a center of the domed portion; and the cylinder further comprise a fusible plug screwed into each the tapped hole.
The liquefiable gas pressure cylinder as above can have the heads be provided with two additional holes which are also tapped; and the cylinder further comprise valves with siphon pipes attached installed in the additional holes.
The liquefiable gas pressure cylinder as above can have the heads have a profile and thickness so that the domed center portions will reverse before any other part of the cylinder is stressed beyond a yield limit for such part.
Another aspect of the invention resides in a method of making a liquefiable gas pressure cylinder comprising the steps of: forming a cylindrical shell including a cylinder body and end portions; forming two heads, each head having a domed center portion and a flanged periphery, the flanged periphery having a cylinder portion surrounding the domed center portion and a radially extending edge portion, an outer diameter of the cylinder portion being equal to an internal diameter of the shell; press-fitting the two heads at opposite ends of the shell with the domed center portion extending axially inwardly, and the cylinder portion being fitted into the end portions of the shell; cold forming the end portions and the flanged periphery radially inwardly; and fusion welding the end portions and the flanged periphery together.
The method as above can further comprise radiographing all welds.
The method as above can further comprise heat treating the welded the end portions and the flanged periphery.
The method as above can further include wherein the cold forming results in a radially inwardly directed bend to the extent of at least 1 inch from straight cylindrical diameters as measured before bending.
The method as above can further comprise prior to forming the heads, determining a profile and thickness so that the domed center portions will reverse before any other part of the cylinder is stressed beyond a yield limit for such part.
The welded, radiographed and chimed ends of the present invention are unique because this design ensures that the stresses in the circumferential weld joints are very low. In the event of accidental over pressure or fall from a truck, if pressure exceeds eight times the working pressure, the container will not burst. One of the dished end will reverse outwardly and internal pressure of the container will come down, which ensures built in safety.
The fusion welding construction of the circumferential joints ensures complete fusion welding between shell and dished end which is verified through radiography. By prototype test followed by finite element analysis and strain gauge testing it has been proved (in case of ISGEC Container) that stress concentration on circumferential joint is lowest. This type of cylinder or drum can withstand 8 times the working pressure without any failure. This is an improvement over the old forging process, where lack of bonding during forging can go unnoticed.
The invention resides not in any one of these features per se, but rather in the particular combination of all of them herein disclosed and claimed and it is distinguished from the prior art in this particular combination of all of its structures for the functions specified.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. Those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the following Abstract of the Disclosure is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms of phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
It is therefore an object of the present invention to provide a new and improved liquefiable gas pressure cylinder which has all the advantages of the prior art liquefiable gas pressure cylinder and none of the disadvantages.
It is another object of the present invention to provide a new and improved liquefiable gas pressure cylinder which may be easily and efficiently manufactured and marketed.
It is a further object of the present invention to provide a new and improved liquefiable gas pressure cylinder which is of a durable and reliable construction.
An even further object of the present invention is to provide a new and improved liquefiable gas pressure cylinder which is susceptible of a low cost of manufacture with regard to both materials and labor, and which accordingly is then susceptible of low prices of sale to industry, thereby making such liquefiable gas pressure cylinder economically available to the businesses that need it.
Still yet another object of the present invention is to provide a new and improved liquefiable gas pressure cylinder which provides in the apparatuses and methods of the prior art some of the advantages thereof, while simultaneously overcoming some of the disadvantages normally associated therewith.
These together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.